The Mater hospital said it has set up a dedicated team to tackle the high level of absenteeism at the hospital after it emerged that an average of 105 workers call in sick every day.
Figures compiled by the hospital showed that 24,594 work days were lost last year due to absences among the hospital's 3,000-plus staff.
When translated into daily figures it transpired that an average of 41 nurses were absent each day, as well as 32 support staff, such as cleaners and security personnel. Administrative and medical staff accounted for the remainder.
In an internal memo earlier this year, the hospital's acting head of human resources Edna Hoare warned staff they were putting themselves at risk of dismissal if the situation continued.
The Irish Nurses Organisation (INO) said yesterday there was no question that their members were trying to fill a quota of sick days or were erroneously claiming illness.
"Nurses would only be absent from work due to illness if they were genuinely sick," INO industrial relations officer Tony Fitzpatrick said.
It was of great concern to the union he said that conditions in the hospital were causing illness among workers.
"The figures are shocking and the level of absenteeism is extremely high, but there are factors contributing to this, including the deficient work environment."
Nurses were facing ever increasing work loads, because a ceiling had been put on staff levels. They were coping with overcrowding and considerable stress, all of which was affecting their health, he said.
In particular, the Mater's A&E department was exceptionally small but had one of the highest rates of attendances of any hospital.
"It is a vicious circle. Staff are overworked, the hospital is short staffed, the environment is poor and that all increases the level of absenteeism," Mr Fitzpatrick said.
In a statement yesterday the hospital said it was addressing these issues.
